Photovoltaic devices are generally understood as photovoltaic cells or photovoltaic modules. Photovoltaic modules ordinarily comprise arrays of interconnected photovoltaic cells.
Thin-film photovoltaic modules, a variety of which is also known as thin-film solar modules, are generally composed of a number of electrically interconnected optoelectronic components. Such components may be optoelectronic devices such as photovoltaic cells and additional optional components such as diodes and other electronic devices.
Multilayer thin-film technologies enable the monolithic integration and interconnection of several optoelectronic components and associated components on a same substrate. This integration is produced in situ using a sequence of layer deposition and scribing techniques. Thin-film optoelectronic or photovoltaic components or devices are essentially composed of a stack of three material layers: a conducting back-contact electrode layer, a semiconductive photovoltaic material layer, also known as the absorber, and another conducting front-contact electrode layer, said front-contact layer usually being transparent. Photovoltaic cells based on semiconductive material such as Cu(In,Ga)Se2 (CIGS) or CdTe show promise for less expensive solar electricity, lower energy payback time, and improved life-cycle impact as compared to traditional wafer-based silicon photovoltaic devices or solar cells.
Compared to wafer-based photovoltaic devices, monolithic photovoltaic modules may have lower costs thanks to reduced material quantities used by thin films, reduced labor costs of monolithic integration, and ease of automatic production of large quantities of photovoltaic modules, for example using roll-to-roll manufacturing techniques. Further savings can be obtained by increasing the relative area of photovoltaic components exposed to light, for example by reducing the area occupied by front-contact grids that collect current over the photovoltaic cell's front-contact electrode, electrical interconnects between optoelectronic components, and busbars. Photovoltaic module production yields may also be increased thanks to a reduction in the number of production steps, for example by reducing or eliminating the step where front-contact grids are added.
Monolithic interconnects are customarily composed in the prior art of mostly parallel scribing lines. The present invention describes a class of monolithic interconnects made of wavy scribing lines. The waviness of said monolithic interconnects in some regions of the photovoltaic module may be tuned to the zonal sheet resistance of the front-contact layer. Such wavy monolithic interconnects may be advantageous for certain applications and module sizes and reduce the need for front-contact grid fingers. The invention is also especially advantageous for thin-film CIGS photovoltaic modules and presents embodiments where photovoltaic modules are not rectangular